Apparatus for layering a liquid composition

ABSTRACT

The invention disclosed is directed to a device for layering a liquid photocurable composition. The device includes an elongate body having along its lower end a recess for spreading liquid composition, and includes arms attached adjacent recess sides for preventing spreading beyond sides of a region which may be traversed by the recess. When used in combination with an assembly also disclosed, the device forms liquid photocurable composition into layers of close tolerance thickness from which articles such as polymeric printing plates may be formed.

llnite 1 States Patent [191 Wessells et a1.

[ Jan. 1, 1974 APPARATUS F OR LAYERHNG A LIQUID COMPOSITION [75] Inventors: Forrest A. Wessells, Baltimore; John P. Conrey, Marriottsville, both of [73] Assignee: W. R. Grace & Co., New York,

[22] Filed: Feb. 23, 1971 [21] Appl. No.: 118,040

[52] US. Cl. 118/100 [51] Int. Cl. 305a 11/04 [58] Field 01 Search 118/100, 413, 126, 118/415, 120, 123; 101/123, 124; 117/102 L, 64 R; 425/218 [56] References Cited UNITED STATES PATENTS 1,170,520 2/1916 Erickson et al 118/262 X 1,490,400 4/1924 Owens 101/123 2,739,530 3/1956 McLaurin 101/123 2,845,858 8/1958 Denley .1 101/123 2,963,964 12/1960 Klump lOl/l23 2,964,806 12/1960 Naegeli 15/256.5l

Primary Examiner-Morris Kaplan Attorney-Eugene M. Bond and Kenneth E. Prince [57] ABSTRACT The invention disclosed is directed to a device for layering a liquid photocurable composition. The device includes an elongate body having along its lower end a recess for spreading liquid composition, and includes arms attached adjacent recess sides for preventing spreading beyond sides of a region which may be traversed by the recess. When used in combination with an assembly also disclosed, the device forms liquid photocurable composition into layers of close tolerance thickness from which articles such as polymeric printing plates may be formed.

1 Claim, 9 Drawing Figures PAIENTEDJAN Hm sum 1 0F 3 ATTOR N E\ 'PATENTEBJAN 11914 SEEUZUFS' INVENTORS FORREST A. WESSELLS JOHN P. CONREY ATTORNEY PATENT'EUJAN H914 sum 3 OF 3 l l/l/l FIG. 7

, O H N 1 m l! m m MP l 8.. 9 T I F W m ENTORS SSELLS BY j E ATTURN EY APPARATUS FOR LAYERING A LIQUID CUMPGSI'IIGN The present invention relates to a new improved device for layering a liquid photocurable composition when used in association with a photocomposing apparatus. The invention also relates to an assembly including the device as a component, and to an improved method for forming liquid photocurable composition into layers from which articles such as polymeric printing plates may be prepared.

Photocomposing units available in the prior art have been complex and have had limited versatility for photocomposing with maximum efficiency. In most instances of the prior art formation of a layer of a photocomposing composition has required use of devices for spreading, followed by use of sensitive knife-edge devices or the like for leveling. Additionally, molds, trim- I ming devices or the like have been required for controlling length and width dimensions of such layers. Prior art attempts to overcome these difficulties generally have been unsatisfactory while proving to be complex and expensive. Accordingly, a substantial need has existed in the art for a suitable, economical means for layering liquid photocurable composition.

It has been found that by practice of the present invention there is provided a device for layering a liquid photocurable composition in a simple, efficient and highly versatile manner. When used in association with a photocomposing apparatus, the device aids in exacting and highly reproducible photocomposing of articles such as polymeric printing plates.

Generally stated, the present invention provides a device having means for spreading a liquid photocurable composition into a layer characterized with a shape controllable principally by the device. The device includes a horizontally elongate body having along a lower end thereof a recess for spreading a liquid composition into a layer. The recess terminates along its lower end to a substantially flat under-body region which aids in leveling the layer during a spreading operation. Arms provided adjacent sides of the recess tend to prevent spreading of the liquid composition beyond the sides of a region traversed by the recess.

By including the device as a component of the present assembly for layering, there is provided a means for spreading liquid composition into a generally rectangular layer which may be characterized with substantially uniform thickness. Conveniently, the present device may include a number of recesses for efficiently forming at the same time a like number of layers.

Broadly stated, the present method for layering includes a step of spreading liquid photocurable composition into a generally rectangular layer of close tolerance thickness over a support'sheet.

Practice of the present invention will become more apparent from the following detailed description taken in connection with the accompanying drawings wherein like numerals refer to similar elements throughout the several views.

In the drawings:

FIG. I illustrates in fragmentary perspective view the present assembly for layering including the present layering device as a component thereof;

FIG. 2 is a fragmentary top plan view of the present layering device;

FIG. 3 is a fragmentary front elevational view of the layering device with arms removed;

FIG. 4 is an enlarged side elevational view of the device taken along line 44 of FIG. 3;

FIG. 5 is an enlarged sectional view of the device taken along line 55 of FIG. 3;

FIG. 6 schematically illustrated in side elevation view a photocuring arrangement for use in the present method;

FIG. '7 is an enlarged fragmentary view of the arrangement of FIG. 6 and illustrates the layering operation of the present device;

FIG. 8 is a fragmentary top plan view illustrating a variation of the present layering device; and

FIG. 9 is a fragmentary front elevational view of the device shown in FIG. 8.

Referring to FIG. I, there is illustrated assembly I0 for layering which includes device I2 as a component thereof. The assembly also includes bench Id, shown in fragmentary view having thereon platform 16 which desirably has a substantially flat top surface. Substantially straight rigid rails 118 are provided for guiding and slidably supporting device 12 in traversing the platform in the present layering operation. Desirably, the rails are substantially parallel, one to the other and each to the platform. The rails may be secured to mounts 2% which in turn are supported by platform 16 generally near corners of the platform. Generally rectangular layers 22 of liquid photocurable composition are illus trated on the platform as they appear after layering liquid composition deposited on the platform prior to use of the device. The layers may be characterized with substantially uniform thickness and substantially straight sides, each of the sides being generally parallel to the other sides. The platform may be, for example, the work area of a photocomposing apparatus which may include an actinic light source for selectively exposing the layers in forming articles such as printing plates. The present invention will become more clearly apparent from the description next given principally with reference to FIGS. 2-5 wherein device 12 is shown in greater detail.

FIGS. 2-5 illustrate device 12 including elongate generally rigid body 24 having attached to face 26 thereof side anns 2b and intermediate arm 29 which may be generally midway along the device. Recesses 30 (FIG. 3) are included in the device transverse length segments of body 24 in lower regions intermediate the arms which include generally vertical sides adjoining the recesses. Recesses 30 assist in carrying out the spreading and leveling functions of the present device, while the arms tend to prevent spreading of liquid composition beyond sides of platform regions which are traversed by the recesses during the layering operation. The recesses include generally arcuate portions M adjoining face 26 along recess edges 32. The recesses further include generally vertical recess portions an extending tangentially from arcuate recess portions M and terminating to recess edges 33 along substantially flat undersurface 4MP. Corner regions 42 of recess portions 34 conveniently may have the generally spherically arcuate surface segments shown. These elbowlike comers aid in forming liquid composition layers having side ends of arcuate shape in elevational section, resulting in a desirable tendency of the layers to resist separation from support sheets on which the layers may be formed. Generally U-shape notches M may be included in ends 46 for receiving support members illustrated by rails 18 of generally circular section. Other suitable shapes may be used for the notches and support rails receivable therein, if desired. However, the notches and rails illustrated are found, in combination, to assist in preparing layers having closer tolerance in thickness and width dimensions.

The device may further include holes 48 extending from front faces of the arms to rear surface 50 of the layering device 12. The holes are provided for receiving guide members appearing in FIG. 1 as generally taut wires 52 which may be slidably received through the holes for reversibly guiding the device in the layering operation. The wire may be in the form of, for example, string, cord, cable, rod or the like, and may be constructed of any suitable material such as steel, nylon, or the like. In a variation, wires 52 may be adapted for advancing the device. For example, one or more of the various wires may be secured to the device and may be operably connected to drive means for reversibly moving the wires over the platform generally in the direction of their longitudinal axes. Numerous known securing means and numerous known drive means may be used with the present device. The device may simply include a handle, not shown, which may be fastened, for example, to hole 54 for advancing the device.

FIG. 4 is an enlarged side elevation view of device 12 and more clearly illustrated the form of substantially flat undersurface 40 in body regions behind the arms. In these regions, undersurface 40 extends generally from a lower edge of face 26 to a lower edge of rear surface 50. If desired, these regions of undersurface 40 may ride on platform surfaces which border sides of generally rectangular platform recesses wherein it may be desired to spread a liquid composition. By using the device in such an arrangement, a convenient means is provided for spreading liquid composition into layers having substantially flat planar surfaces which may be generally coplanar with the platform surfaces on which the device may ride.

FIG. 6 illustrates photocuring arrangement 56 in schematic side elevation view. The arrangement includes platform 16 having thin support sheet 58 removably disposed in generally flat position thereon. Lamp 60 having generally parabolic reflector 62 associated therewith is provided above the support sheet for directing actinic radiation to a liquid photocurable composition after the composition is layered over the support. A layer of composition may be formed on support sheet 58 by spreading deposited puddle 64 of a liquid photocurable composition using device 12 which is illustrated generally in conjunction with the arrangement. The puddle is shown schematically in side end view and conveniently may be received on support 58 along an end thereof. Device 12 is shown in the view as the device typically appears relative to the received puddle of composition prior to spreading.

FIG. 7 is an enlarged fragmentary view generally of the platform area of arrangement 56 and more clearly illustrates the layering operation of the present device. After puddle 64 of liquid photocurable composition is received onto support sheet 58, device 12 is advanced over the support sheet. For layering, device 12 is supported as by means of rails 18 positioned above the platform such that the device is spaced above the sheet at a distance substantially equal to a layer thickness desired. Recess 30 of the advancing device contacts an upper portion of the deposited liquid composition effecting substantially uniformly thick layer 22 of composition on support sheet regions over which the device recess passes. As the device continues to advance in the direction shown by arrow 66, residual unlayered composition 68 is spread in like manner over the support sheet to complete the partly completed layer illustrated.

FIGS. 8-9 illustrate in fragmentary top plan and front elevation views, device 70 which is a variation of device 12. Device 70 is substantially the same as device 12 except including no arms intermediate side arms 28, while a single recess extends from a first side arm and terminates to a second side arm. In this variation, the device may be used in forming a liquid composition into a generally rectangular layer of width substantially equal to the length of the single recess. It is to be understood, however, that any suitable number of intermediate arms, illustrated by arm 29 of device 12, may be included in the present device, thus permitting simultaneous preparation of a number of liquid composition layers.

Although recesses having a variety of shapes may be included in the present device, recesses generally of the shape shown are found excellent for effecting substantially uniform thickness of a liquid composition layer, while tending to prevent waste of composition such as often occurs using heretofore known devices for spreading. The recess illustrated tends to prevent roll up of liquid photocurable composition onto the device in regions thereof other than the recess which may contact the composition in a layering operation.

While the present device may be used to effect layering of compositions into layers of a variety of thicknesses, the device may conveniently serve for layering compositions into thin layers having substantially uniform thickness throughout and substantially flat top surfaces. For example, composition layers having substantially uniform thickness in the range from about 10 to about 250 mils may be repeatedly and reproducibly formed using the present device and method.

Support sheets for use in the present invention may be formed of any suitable material such as, for example, polyethylene terephthalate film products, glass, fiber-reinforced glass, rubber, steel, aluminum and the like.

The present device may be simply formed using a variety of suitable known forming methods. The device may simply and efficiently be constructed, for example, from an appropriate piece of steel stock for use as the body portion. The various notches, holes and recesses may be provided using known forming means therefor. The device may be formed either of one-piece construction, or the various arms may be separately formed and attached to the body using any suitable attaching means therefor. Generally, greater uniformity of layer surfaces may be effected where the device is fonned having a substantially smooth undersurface. In use, the present assembly exhibits greater layering efficiency when the rails and notches are formed of lowfriction surfaces, while liquid composition layers which may be formed are generally of closer tolerance thickness.

The term liquid photocurable composition as used herein means a liquid composition generally having a viscosity in the range from slightly above 0 to about 20 million centipoises at 70 C. which is solidified either by photocuring or photopolymerizing or both on exposure to radiation from actinic light. A number of these compositions are taught in US. Pat. No. 3,537,853 to Wessells and Gush.

The present invention will be further illustrated by the following non-limiting example.

EXAMPLE Two inch X 21 inch rectangular sheets of 4 mil thick Mylar, trademark for a polyethylene terephthalate product by DuPont, were placed on the flat platform of an assembly having a construction generally as illustrated by assembly 10 of FIG. ll. Initially, the slidably supported layering device was at rest above an end of the platform with recesses of the device generally facing the opposite end of the platform The Mylar sheets were placed with their longer sides parallel to the rails of the assembly in an arrangement generally as illustrated for liquid photocurable composition layers 22 in FIG. 1. Next, there was poured onto one of the Mylar sheets, along a width region near an end thereof, a liquid photocurable composition in the form of a puddle having an overall length of 14 inches and a height of greater than mils substantially throughout. A like puddle was then deposited in like manner on the other Mylar sheet. Each puddle extended from about 0.5 inch inside a first side of its Mylar sheet and terminated about 0.5 inch from an opposite side thereof.

After the puddles of liquid photocurable composition were received on the Mylar support sheets, the device was started in motion from its rest position with its recesses generally facing the puddles. The device used was generally of the construction illustrated by device 12 in the appended drawings. U-shape notches of the device were snugly but slidably received about l-inch diameter circular receiving rails which were supported by support members associated with the platform. The rails were substantially parallel with each other and with the platform surface. Arms of the device were about 1 inch in height and had smooth undersurfaces. The device included two recesses, each of about 14 inches in length as measured from an inner side of its adjacent side arm to a nearer side of the intermediate arm. Each recess included a lower vertical region about 1 inch in height and an arcuate region generally thereabove of about 1 inch radius. The smooth, flat undersurface of the device was about 24 mils above the platform. As the device was moved along the rails, the puddles of liquid photocurable composition were contacted in regions above a clearance zone of 20 mils thickness measured from the Mylar sheets. As the lay ering operation was continued, the device spread the composition into two 14 inch wide rectangular layers on the support sheets with'diminishing amounts of unlayered composition substantially encompassed within the recesses of the device while it was advanced across the platform. After the device completed its travel over the Mylar sheets, the operation was stopped.

The thus formed layers were thereafter exposed imagewise to actinic radiation projected selectively through image-bearing transparencies mounted in a holder approximately 250 mils above the photocurable layers. The layers were found to be cured clear through by exposing to a xenon lamp at an intensity of 3,000 microwatts/cm for about 3 minutes to form two developable polymeric printing plates. Thereafter the Mylar sheets having thereon cured composition in the exposed regions and substantially non-cured composition in unexposed regions were removed from the assembly. The non-cured composition were removed by directing jets of water against the selectively cured composition layers which was then observed. Average thickness of these printing plates was shown to be of close tolerance by measurements at randomly selected positions on the plates. Dimensional stability of these plates and fidelity of reproductions on printing were found to be superior to printing plates prepared from photocurable composition layers formed using methods heretofore known in the art.

It is to be understood that the foregoing detailed description is given merely by way of illustration and that various modifications may be made therein without departing from the spirit or scope of the present invention.

What is claimed is:

1. An assembly for layering a liquid photocurable composition rail assembly comprising:

A. a platform having a substantially flat surface for supporting, thereon, a substrate receiving said composition;

B. a guide rail operatively associated with at least each of a pair of parallel upper edges of said platform;

C. a movable doctor plate having a smooth, planar undersurface, extending transversely between said rails and including means slidably receiving said rails whereby said plate is supported for guided movement and said undersurface operatively associated with the coated substrate;

D. the functionally leading face of said doctor plate having at least a pair of recessed sections, each section extending vertically from the functional edge of said face and along the longitudinal extent of said plate beyond the width of the associated substrate support surface of the platform and said recess being so arcuately configured as to retain the unformed liquid composition therein;

E. said platform being adapted to support a substrate with respect to each recessed section of the doctor plate;

F. a plurality of arms extending horizontally from a vertical face of said plate;

G. each of said arm being parallel to said rails, being laterally spaced from an associated side of a substrate, and having an undersurface coplanar with that of the plate undersurface;

H. a plurality of apertures extending longitudinally through each of said arms and configured to each closely and slidably receive a filamentary element therethrough;

. a guide means comprising a plurality of filamentary elements, generally coextensive with and parallel to said rails, operatively associated with said platform and extending through said apertures; and

J. means imparting movement to said plate;

K. whereby said doctor plate is guided for guided movement along said rails and said guide means to effect said layering of the photocurable composition. 

